1. Field of the Invention
This invention relates to an electrical connection socket, particularly for an explosive or explodable atmosphere, for example in the form of a power connector socket or a mobile extension cable socket, and its manufacturing process.
2. Discussion of Background Information
It is already known how to manufacture an electrical connection socket provided with electrical contacts installed in contact housings of an insulating block, and which are designed to cooperate with the corresponding contact pins of a plug.
An xe2x80x9cexplosion proofxe2x80x9d enclosure needs to be provided for each connection area in order to make a socket particularly suitable for an explosive atmosphere.
In the past, this type of explosion proof confinement was obtained using intermediate mobile contacts, for example in the form of pistons moving in translation as described in European patent 0 112 258.
However one of the difficulties with this type of device is the reliability of the disconnection time between the contact pistons and the electrical contacts between the plug and socket to prevent breaking outside the explosion proof area, particularly when the plug is extracted suddenly.
Known practice also includes a connection socket like that described in document GB 2 125 234 A that is provided with a safety disk with a peripheral opening for each peripheral contact housing in the insulating block of the socket, and that it is installed free to rotate on the insulating block through a central opening in the block, and in which the inside surface cooperates with a lateral surface of a central protuberance from the insulating block forming a rotation hub, such that the peripheral openings in the disk may be moved at will by rotating this disk with respect to the corresponding housings on the insulating block.
Furthermore, if this type of device is to be used in an explosive atmosphere, an explosion proof joint surface is created between the inside surface of the casing of the plug that is inserted in the socket, and the outside surface of an element fixed to the insulating block of the said socket.
It can then be understood that the body of the plug must fit precisely while being plugged in, to form the above-mentioned explosion proof joint surface. It is usually difficult to make a large diameter explosion proof joint and requires the use of metal parts as described here for precision reasons.
Furthermore, this part is vulnerable and the slightest damage can reduce the efficiency of the explosion proof joint surface.
The invention provides for an electrical connection socket comprising an insulating block comprising a central protuberance. A plurality of peripheral contact housings are arranged in the insulating block. Each peripheral contact housing includes an electrical contact. Each peripheral contact is adapted to mate with a corresponding pin when the electrical connection socket is coupled to an electrical connection plug. A safety disk is provided having a central opening and at least a same number of peripheral through openings as there are electrical contacts. The central opening of the safety disk is adapted to receive at least a portion of the central protuberance of the insulating block.. The safety disk is rotatably mounted to the insulating block so as to form an explosive proof joint between at least two surfaces.
The safety disk may be rotatably mounted to the insulating block so as to be movable between at least a first position wherein the peripheral openings of the safety disk are aligned with the electrical contacts, and at least a second position wherein the peripheral openings of the safety disk are not aligned with the electrical contacts.
Each electrical contact may be mounted in a corresponding peripheral contact housing in the insulating block. The central opening of the safety disk may be arranged to be rotatably disposed adjacent the central protuberance of the insulating block, such that the safety disk is free to rotate on the central protuberance of the insulating block. Each of the safety disk and insulating block may comprise an engaging surface, such that contact between at least two engaging surfaces may be adapted to form an explosion proof joint. The socket may be adapted to operate in an explosive atmosphere. The central protuberance of the insulating block may comprise a central opening adapted to receive a central pin disposed in the electrical connection plug, when the electrical connection plug is coupled to the socket.
The socket may further comprise an electrical contact disposed in the central opening of the insulating block. Each of the safety disk and the insulating block may have planar front engaging surfaces that contact each other such that at least part of these front engaging surfaces are adapted to form an explosion proof joint.
The socket may further comprise an explosion proof joint formed between at least two contact surfaces of the safety disk and the insulating block. The at least two contact surfaces may be formed between the central opening of the safety disk and a cylindrical surface of the central protuberance of the insulating block. The central protuberance of the insulating block may be integrally formed with the insulating block. The central protuberance of the insulating block may comprise an insulating material. The safety disk may comprise a peripheral annular extension which is adapted to one of cover and overlap at least a portion of the insulating block. The peripheral annular extension may rotatably engage the insulating block via at least two contact surfaces, the at least two contact surfaces forming an explosion proof joint. Each of the safety disk and insulating block may comprise at least three corresponding contact surfaces, an explosion proof joint being formed via contact between at least one surface of the safety disk and at least one surface of the insulating block.
The socket may further comprise an explosion proof joint being formed via contact between at least two surfaces of the safety disk and at least two surfaces of the insulating block, one of the at least two surfaces being movable with respect to the other. The socket may further comprise a plurality of elements, wherein each element is adapted to close a peripheral contact housing. Each element may be disposed in the insulating block and arranged adjacent an end of a corresponding electrical contact which is opposite an end which is disposed adjacent the safety disk.
The central protuberance may comprise a hub which includes at least one cylindrical surface. The hub may comprise at least one of a flared external surface and recessed inner surface. The central opening of the safety disk may comprise a surface which corresponds to the at least flared external surface of the hub. At least one of the electrical contacts may comprise an end to end pressure contact. The at least one end to end pressure contact may comprise a contact head, a braid, and a helical spring.
The insulating block may be rotatably connected to the safety disk via insert molding, the safety disk being rotatably fixed to the insulating block after the insert molding.
The invention next provides for an electrical connection socket comprising an insulating block comprising an insulating central cylindrical hub. A plurality of peripheral contact housings are arranged in the insulating housing. Each peripheral contact housing includes an electrical contact. Each peripheral contact is adapted to mate with a corresponding pin when the socket is coupled to an electrical connection plug. A safety disk is provided which comprises a central opening and at least a same number of peripheral through openings as there are electrical contacts. The central opening of the safety disk is adapted to receive at least a portion of the cylindrical hub of the insulating block. The safety disk is rotatably mounted to the insulating block such that the safety disk engages the insulating block via at least one contact area.
The at least one contact area may be defined by contact between the cylindrical hub and the central opening of the safety disk. At least another contact area may be defined by contact between a surface of the insulating block and a surface of the safety disk.
The invention further provides an electrical connection socket comprising an insulating block comprising an insulating central hub and a central contact housing adapted to receive a central electrical contact. A plurality of peripheral contact housings are arranged in the insulating block and surrounding the central electrical contact. Each peripheral contact housing includes an electrical contact. Each peripheral contact is adapted to mate with a corresponding pin when the socket is coupled to an electrical connection plug. A safety disk is provided which comprises a central opening and a plurality peripheral through openings. The central opening of the safety disk is adapted to receive at least a portion of the insulating central hub of the insulating block. The safety disk is rotatably mounted to the insulating block and forms an explosive proof joint.
In particular, this is why the invention proposes a connection socket provided with a safety disk as mentioned above, but which is particularly remarkable in that at least some of the surfaces in contact with the safety disk and the insulating block and the inside surfaces of at least some of the peripheral openings in the safety disk and the outside surfaces of the corresponding pins in the plug form the surfaces of the explosion proof joint such that at least the peripheral housings in the contact of the insulating block form at least one explosion proof enclosure.
However, it is obvious that this type of structure does have advantages for use even when there is no explosive atmosphere.
In one embodiment, the central protuberance or the hub of the insulating block may be drilled to allow passage of the central pin of the plug designed to cooperate with a contact formed in a central housing of the insulating block.
For example, the safety disk and the insulating block have plane front surfaces that come into contact with each other, and in which at least part forms an explosion proof joint surface and/or furthermore the explosion proof joint surfaces between the safety disk and the insulating block are composed at least partly of at least part of the lateral rotation surface of the insulating block hub and the inside surface of the central opening of the disk.
According to one embodiment, the safety disk is provided with a peripheral annular extension that covers part of the insulating block, at least part of the overlapping areas of the insulating block and the extension forming the rotating lateral surfaces of the explosion proof joint.
In this case and according to one embodiment, the rotating lateral surfaces of the insulating block and the safety disk formed firstly by the hub and the central opening in the disk, and secondly by the overlapping areas of the insulating block and the disk extension, are cylindrical surfaces of revolution. This type of embodiment is not compulsory since the rotating surfaces, although they must be surfaces of revolution, do not need to be cylindrical.
At least the peripheral contact housings may for example be closed at the bottom of the corresponding contacts by elements forming explosion proof joint surfaces in the housings.
Preferably, the hub of the insulating block has a flared and recessed end that holds the disk and the insulating block fixed together in translation.
According to one advantageous but not exclusive embodiment, the contacts of the socket are pressure contacts in end to end contact, each provided with a contact head, a braid and a helical spring located in the corresponding contact housing.
It is known that high precision is necessary for the interstices and the lengths of the explosion proof joints.
The invention also proposes a particular non-compulsory molding process which is remarkable in that the insulating block is insert molded in or on the safety disk, itself made in advance and acting as an insert, the necessary and adjusted interstice or clearance between surfaces of parts in contact to allow rotation of the disk on the block and to form the explosion proof joints being created by removal of material from the block after molding.